If you're model is the one capecoaler posted, it looks like it would be hard to maintain a coal fire in it. To burn coal well in a hand fired unit, the entire bottom of the firebox must be grates especially if the coal you're using produces a lot of ash.
lauriecoke wrote:Our local guy suggested that we put bricks along the side to create a V so that everything will flow down to where the shaker grates are.
Your "local guy" is on the right track but it would be best if the bricks are as close to vertical as possible. You want the ash to settle directly on the grates so when you shake it will easily fall through and not get "stuck" on anything, like the slope of the fire bricks for instance.
You could try to position fire bricks to keep the coal bed completely on the grates.
Whatever you do, don't give up.